One of the simple ways to understand whether you have root-access on your device is by using the Root Checker app. You can install it to your device on Google Play. You'll see a string with the name of your device in the middle of the screen and a big button with the 'Verify Root Access' label upon launch. Press the button and launch the verification process.
If the device does not have root access granted, you'll see the “Sorry! This device does not have proper root access” message.
If the device has root access granted, , you'll see the “Congratulations! This device has root access!” message.